Application of liquid chromatography-electrospray-tandem mass spectrometry for the identification and characterisation of linear alkylbenzene sulfonates and sulfophenyl carboxylates in sludge-amended soils

A novel procedure was developed for the simultaneous determination of linear alkylbenzene sulfonates (LAS) and their major metabolites, sulfophenyl carboxylates (SPC), in sludge-amended soil. After pressurised liquid extraction with methanol/water (90:10) and a clean-up on C18 solid-phase extraction cartridges, final analysis was done by ion-pair liquid chromatography-electrospray-tandem mass spectrometry (LC-ESI-MS/MS). With this method, SPC with 5-13 carbon atoms in the aliphatic side chain were identified for the first time in agricultural soils treated with sewage sludge. Quantification of LAS and SPC in soil from 10 field sites, which differed in the history of sludge application, gave total concentrations of 120-2840 μg kg−1 for LAS and of 4-220 μg kg−1 for SPC. The data provided evidence for rapid biodegradation of LAS in the initial phase after sludge amendment with a transitory build-up of high concentrations of, mainly, short-chain SPC. Trace amounts of residual LAS and SPC were detected in soils having received the last sludge treatment 10 days to 4 years prior to sampling.